You can use the model maker. It is very friendly: You have to create a variable box (place a raster object in the model) and then introduce a function box in wich you have to insert the NDVI function.

I think that model maker is available in Erdas 9.3....

Probably Juan is right. not much experience with ERDAS, am a PCI user and is very much there, easy and straightforward. If you need procedure do let me know.

Hi,

I am using Erdas imagine version 9.1 but i haven't used Erdas 9.3. In Erdas 9.1 you could calculate NDVI by using the model maker as Juan said but also there is a more straightforward procedure. From the Erdas imagine 9.1 icon menu select Interpreter-->Spectral Enhancement-->Indices then choose NDVI function and the sensor. In your case Landsat MSS. Check if the procedure is the same also for Erdas 9.3.

Best regards

Click on Interpreter - Spectral Enhancement - Indices. NDVI is one of the choices?

I would suggest that you try both the available NDVI tool as well as build a NDVI model yourself. And see the results.

I think you did a mistake in rastar calculation. Use (b4-b3)/(b4+b3). Don't forget to use brackets.

I think i would agree with Aditi. As a third year GIS student we have not come across NDVI calculations yet. The software we are utilizing right now is Erdas 8.5 and 9.1.